65 Examining the Tropopause Structure during Rossby Wave Breaking Events with COSMIC

Monday, 23 January 2017
Alexia Prosperi, ESMEI at Colorado State University, Fort Collins, CO; and C. Liu and E. A. Barnes

Rossby waves are instrumental to atmospheric dynamics and their breaking can transport and mix the air around the tropopause.  Here, we examine the structure of the tropopause throughout the lifecycle of Rossby wave breaking to quantify impacts on the frequency of double tropopauses identified from COSMIC GPS radio occulation profiles.  While double tropopauses have been previously examined with COSMIC, this work goes one step further to investigate their occurrence in the presence of large-scale dynamical processes (i.e. Rossby wave breaking).  We investigate the tropopause structure throughout the life cycles of two types of Rossby wave breaking, cyclonic and anticyclonic, and diagnose whether these two types impact the structure of the tropopause differently.  Our results indicate that the effects of the two types of wave breaking may indeed differ, although similarities are also found.  Specifically, during cyclonic wave breaking events, double tropopause frequency appears higher in the cyclonic lobe of the overturning, while for anticyclonic events, double tropopause frequency appears higher in the anticyclonic lobe of the overturning.  Additionally, at the end of the wave breaking life cycle, cooling occurs within the cyclonic lobe and warming occurs in the anticyclonic lobe for both event types.  Differences in tropopause structure between cyclonic and anticyclonic wave breaking events are important since the prevalence of each wave breaking type is a strong function of latitude.  Furthermore, it is expected that cyclonic wave breaking will become less frequent as the climate warms and the jet-streams shift poleward, potentially driving changes in the frequency of double tropopauses.
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